For many dental, oral surgery and facial surgery procedures, the administration of a nitrous oxide/oxygen mixture may be desirable. The nitrous oxide/oxygen mixture is administered as an analgesic and relaxant for the patient. The mixture is delivered to the patient through a mask that directs the mixture to the patient but must allow unobstructed access to the surgical area. During such procedures, it is therefore important to prevent or minimize intrusion into the surgical area; any mask utilized for the administration of the nitrous oxide/oxygen mixture must be as small as possible while nevertheless providing proper delivery of the mixture to the patient and preventing escape of the mixture into the work area. Further, since nitrous oxide is continuously administered to the patient during the procedure, and the patient remains awake, slight movements of the patient are to be expected which may dislodge or cause movement of the administering mask during the procedure; such movements should not be permitted to cause significant patient/mask relative motion.
As the nitrous oxide/oxygen mixture is provided to the mask for inhalation by the patient, the escape of any such gas into the surgical work area must be prevented to avoid recognized health hazards to surgeons and staff who may be regularly exposed to such escaping gases during repeated procedures.